1. Field of the Invention
This invention is an accessory device useful for extending the integral material support platform common to some portable tools such as portable radial arm saws and portable miter saws of the types commonly used in carpentry. Our material support platform-extensions are additionally structured for cooperative use with a foldable, portable work bench which has a raised bench top supported by elongated legs, and further having an adjustable gap running the full length of the bench top surface for use in clamping objects. The most common of these portable work benches available on the market is sold under the trade name of "Workmate", which is described on the packaging as a work bench vise, and is manufactured and sold by Black and Decker, Inc., 70-T Joppa Rd., Towson, Md. 21204 U.S.A.
2. Description of the Prior Art
Although our invention is applicable to portable power radial arm and miter saws, and possibly other similar tools such as small portable wood surface planers and small portable table saws all of which include integral material support platforms, for the sake of briefness and simplicity, a portable power miter saw will generally be the portable tool primarily described in relationship to the invention of this disclosure.
Miter saws are primarily used in carpentry for making angled and transverse cuts in baseboard, crown molding, door casings, and other interior and exterior building materials. The majority of miter saws used today in carpentry are portable electrically powered units which include a short horizontal material support platform with a vertical rear material guide fence and an adjustably positionable circular saw hingedly affixed to and supported above the material support platform. Typical portable power miter saws additionally have short support legs affixed to the bottom surface of the material support platform. The short support legs of the miter saw position the top surface of the material support platform of the saw only about 10 to 15 centimeters above the surface which the miter saw is set on. The purpose of the material support platform of a miter saw or like tool is to give the operator a surface on which to rest a board or member in order to stabilize the board while feeding and guiding the board into a saw blade. The guide fence typically attached to the material support platform of miter and radial arm saws further assist the operator in stabilizing and guiding the board, and positioning the board at a given angle relative to the saw blade.
One reason for the wide popularity of portable power miter saws are their portability, typically weighing less than 20 kilograms, and therefore they can easily and quickly be transported to and from the job-site, and about the job-site for convenient and efficient use close to the work. The reasoning for the shortness of the support legs and the short material support platform of a portable miter saw or like tool is to keep the tool highly portable and light in weight.
The miter saw is intended to allow the various angles as well as straight cuts to be made accurately. However, the short horizontal material support platform of a portable miter saw makes it difficult for accurately making cuts in long material as the unsupported end of the material not resting on the short material support platform of the miter saw tends to pull downward under its own weight, thus pulling the opposite end of the material upward toward the saw blade. This tends to frequently result in an unintentional slight bevel or irregular cut. To compensate for this effect, the carpenter must forcefully hold the end of the material to be cut against the platform surface and guide fence of the saw, which can be difficult as the carpenter must also correctly position the material, and operate the saw at the same time. The requirement of the carpenter having to forcefully hold or press one end of the long material downward onto the material support platform of the miter saw adjacent the rotating saw blade is also dangerous, being somewhat analogous with cutting an object with a very dull knife, where due to the degree of pushing force, slipping and injuring one's self can easily occur. Additionally, it should be noted that portable miter saws on construction sites are very often set on the floor, a situation requiring the carpenter to repeatedly bend down during the workday which can lead to fatigue and reduced productivity.
Since the material support platform of the miter saw is short, normally in the range of 40 to 60 centimeters in length, there is no feasible way to provide a stop block or length gauge block to which to abut the end of an elongated board to be cut, which would eliminate the necessity of marking the location where the material was to be cut. Stop blocks are particulary useful when cutting a plurality of pieces all to the same length. Without a stop block, each piece of material to be cut must be individually marked before cutting. This is not only time consuming for the carpenter, but there is also more room for error in measurement.
Since many carpenters already own a work bench vise of the type previously described, material support platform-extensions for a miter saw or like tool which could be used in conjunction with a work bench vise would offer significant advantages. Other structural arrangements of material support platform-extensions not specifically structured for use with the work bench vise as a raised platform, would necessarily have to provide an additional raised platform or table to support the miter saw if the miter saw were to be raised significantly upward to eliminate the need for the carpenter to be repeatedly bending downward during the workday. This additional raised platform or bench, in addition to a work bench vise that many carpenters already have, would add weight and consume more of the already limited space available in the carpenter's vehicle. Therefore, there is a need for a lightweight, easily assembled material support platform-extension for a portable miter saw or like tool which is compatible with existing work bench vises currently available in the market and already owned by large numbers of craftsmen.
A past art patent search was conducted at the U.S. Patent and Trademark Office to examine devices pertinent to our invention, and the following are considered relevant:
Viazanko was granted U.S. Pat. No. 4,798,113, on Jan. 17, 1989, for EXTENSION TABLE APPARATUS FOR POWER SAW. Viazanko's device includes a support base for a miter saw and a two-piece extension table. The extension tables have two foldable telescopic legs on one end, with the second opposite end of each extension table attachable directly to the ends of the miter saw with a detachable connection. This detachable connection requires attachment of a support angle or bracket to the miter saw table. A single smaller hinged leg is also attached to the second end of both extension tables for use in supporting the structure on a work bench when the support base is not used.
On Jan. 17, 1978, Kreitz was issued U.S. Pat. No. 4,068,551 for an EXTENSION TABLE FOR POWER SAWS. Kreitz's device teaches a folding extension table for radial arm saws and the like already having a support table. The extension table is also affixed to the table surface of the radial arm saw with bolts.
Marcoux et al teaches a COLLAPSIBLE WORK TABLE in U.S. Pat. No. 3,342,226, issued Sept. 19, 1967. Marcoux's device includes a support table for a power tool with an attachable accessory extension table. The extension table does not have a guide fence nor means for supporting a stop block.
None of the related past art devices we are aware of are specifically structured for, nor suitable for use with a portable work bench vise supporting a portable power miter saw or like tool, nor are they structured similar to our invention. Although Viazanko's device might at first glance appear to be structured similar to our invention, it includes no structuring for quickly adjusting the height of the material support platform extension when being clamped within a work bench vise. Therefore a great deal of time would generally be required for adjusting the height of Viazanko's extension tables when used in conjunction with the portable work bench vise to provide level surfaces with that of the miter saw resting on the work bench. With Viazanko's device this adjustment procedure would also have to be done each time the extension tables were used. Additionally, although Viazanko's device does include a short hingidly attached support leg somewhat adjacent one end of each of his left and right table extensions, the short support legs are intentionally set back a sufficient distance from the end of the table extensions which abut the saw in order to clear the base to which the miter saw is bolted. This "set back" placement of Viazanko's short hingidly attached legs would prohibit the clamping of his short legs into the clamp of a work bench vise while reserving sufficient room between the clamped left and right table extensions to set a miter saw. Although Viazanko does provide a quick clamping structure for attachment of the extension tables directly to the miter saw table, attachment of a support bracket to the miter saw is required. This attachment apparently requires permanent alteration of the miter saw table by the drilling of holes. This is initially quite time consuming, and further permanently alters and possibly weakens the miter saw.